The Comparison of Toluene Removal Rate in Two Photocatalytic Oxidation Systems of ZnO and TiO2 Nanoparticles on SiO2 bed

Hamed Hassani, Neda Nazarpour, Gholamhossein Pourtaghi

Abstract


Volatile organic compounds (VOCs) are one of the main group of air pollutants. Photocatalytic oxidation is one of the destructive methods for gaseous pollutants and has been received more attention in the past years. In this study investigated the comparison of the toluene removal efficiency by Photocatalytic Oxidation of Toluene by ZnO/SiO2 and TiO2/SiO2. In this study, the effect of parameters such as the amount of relative humidity, initial concentration of pollutant, the apparent speed of gas and the minimum speed of fluidizing of bed on the process of photocatalytic oxidation of Toluene is examined by comparison between TiO2/SiO2 and ZnO/SiO2 catalysts in a fluidized bed reactor. as it was explained, by absorption of water molecules on the surface of the catalyst and converting them to hydroxyl active radicals, these radicals act as a pushing factor in the reaction. The study also showed that an increase in the relative humidity in the 15–45% range would increase the efficacy of toluene oxidation. Conversion percentages between TiO2/SiO2 and ZnO/SiO2 catalysts were not significantly different (pv>0.05), while the reaction rate of ZnO/SiO2 catalyst was higher than TiO2/ SiO2 catalyst (pv<0.05). In the study of the interaction between the apparent velocity variables, initial concentration of toluene and loading of zinc oxide and titanium dioxide, only the interaction between two gas velocity variables and initial concentration of toluene was significant. The results showed that ZnO/SiO2 catalysts generally have a larger efficacy than TiO2/SiO2, presumably because ZnO/SiO2 has more active sites. Additionally, the ZnO/SiO2 catalysts offer better fluidity than TiO2/SiO2. The photo catalytic transformation rate of the pollutant is relatively low, as the optimum humidity level for appears to be 45%.

Keywords


Photocatalysis; Toluene; ZnO/ TiO2; TiO2/SiO2; Fluidized bed Reactor

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References


. Jonidi Jafari A, Rostami R, Rezaei R, Gholami M. Influence of pollution loading and flow rate on catalytic BTEX removal with a combined Cu2O, Fe0 /Zeolite bed. Iranian Journal of Health, Safety & Environment. 2014; 1(1): 9-15.

.Parmar GR, Rao N. Emerging control technologies for volatile organic compounds. Critical Reviews in Environmental Science and Technology. 2008; 39(1): 41-78.

.Kazuhito H, Hiroshi I, Akira F. TiO2 Photocatalysis: A Historical Overview and Future Prospects. Japanese Journal of Applied Physics. 2005; 44: 8269–85.

.Shokoohi R, Zolghadrnasab H, Shanesaz S. Comparison of the Performance of AOP Method Using O3/H2O2 in the Presence of TiO2 and ZrO2 Nano Particles Stabilized on Pumice for the Removal of Pentachlorophenol from Aquatic Solution: Kinetic Studies. Iranian journal of health, safety and environment, 2018; 5(4);1082-90

.Lacombe S, Keller N. Photocatalysis: Fundamentals and applications. Environmental Science and Pollution Research. 2012; 19(9): 3651-54.

.Landi S, Carneiro J, Ferdov S, António , Fonseca M, Manuel F, Pereira R. Photocatalytic degradation of Rhodamine B dye by cotton textile coated with SiO2-TiO2 and SiO2-TiO2-HY composites. Journal of Photochemistry and Photobiology A: Chemistry. 2017; 346(1): 60-69.

.Belver C, José M, Muñozb L. Palladium enhanced resistance to deactivation of titanium dioxide during the photocatalytic oxidation of toluene vapors. Environmental. 2003; 46: 497–09.

.Obee TB, Hay S. Effects of moisture and temperature on the photooxidation of ethylene on titania, Environmental Science and Technology. 1997; 31: 2034–38.

.Li J, Zhou L. Enhanced fluidization bed methanation over a Ni/Al2O3 catalyst for production of synthetic natural gas, Chemical Engineering Journal. 219 (2013) 183–89.

.Prieto O, Fermoso J, Irusta R. Photocatalytic degradation of toluene in air using a fluidized bed photoreactor. International Journal of Photoenergy, 2007; ID 32859, doi:10.1155/32859: 1-8.

.Šuligoj A, Lavrenčič-Štangar U, Ristić A, Mazaj M, Novak Tušar N. TiO2–SiO2 films from organic-free colloidal TiO2 anatase nanoparticles as photocatalyst for removal of volatile organic compounds from indoor air. Applied Catalysis B: Environmental. 2016; 184(5): 119-31.

.Pronina N, Klauson D, Moiseev A, Deubener J, Krichevskaya M. Titanium dioxide sol–gel-coated expanded clay granules for use in photocatalytic fluidized-bed reactor. Applied Catalysis B: Environmental. 2015; 178: 117-23.

.Kim MJ, Nam W, Han J. Photocatalytic oxidation of ethyl alcohol in an annulus fluidized bed reactor. Korean Journal of Chemical Engineering. 2004; 21(3): 721-25.

.Gaya, UI, Abdullah AH. Heterogeneous photocatalytic degradation of organic contaminants over titanium dioxide: a review of fundamentals, progress and problems. Journal of Photochemistry and Photobiology C: Photochemistry Reviews, 2008; 9(1): 1-12.

.Li Y, Wu H. Role of moisture in adsorption, photocatalytic oxidation, and reemission of elemental mercury on a SiO2-TiO2 nanocomposite. Environmental science & technology. 2006; 40(20): 6444-48.

.Dhada I, Nagar P, Sharma M. Challenges of TiO2-Based Photooxidation of Volatile Organic Compounds: Designing, Coating, and Regenerating Catalyst , Ind. Eng. Chem. Res. 2015; 54 (20): 5381–87.

.Herrmann J. Fundamentals and misconceptions in photocatalysis. Journal of Photochemistry and Photobiology A: Chemistry. 2010; 216(2): 85-93.

.Herrmann J. Titania-based true heterogeneous photocatalysis. Environmental Science and Pollution Research. 2012; 19(9): 3655-65.

.Huang Y, Sai S,Ho H, Lu Y. Removal of Indoor Volatile Organic Compounds via Photocatalytic Oxidation: A Short Review and Prospect , Molecules. 2016; 21(1) 56, doi:10.3390/21010056.

.Singh P, Borthakur A, Srivastava N. Photocatalytic Degradation of Benzene and Toluene in Aqueous Medium , Pollution. 2016; 2(2): 199-10.

.Kuo H, Wu C, Hsu R. Continuous reduction of toluene vapours from the contaminated gas stream in a fluidised bed photoreactor. Powder Technology. 2009; 195(1): 50-56.

.Raillard C, Héquet V, Cloirec PL, Legrand J. TiO2 coating types influencing the role of water vapor on the photocatalytic oxidation of methyl ethyl ketone in the gas phase. Applied Catalysis B: Environmental. 2005; 59(3): 213-20.

.Chen J, Qin Y, Chen Z, Z,Yang W, Wang Y. Gas circulating fluidized beds photocatalytic regeneration of I-TiO2 modified activated carbons saturated with toluene. Chemical Engineering Journal. 2016; 293(1): 281-90.

.Yao S, Kuo H. Photocatalytic degradation of toluene on SiO2/TiO2 photocatalyst in a fluidized bed reactor. Procedia Engineering 2015;102: 1254–60.




Iranian Journal of Health, Safety and Environment e-ISSN: :2345-5535 Iran university of Medical sciences, Tehran, Iran